Supernovae, Black Holes Ned Stark & Jon Snow Seen Shredding Stars

A new astronomical project, the Zwicky Transient Facility (ZTF), is surveying the sky from California Institute of Technology (Caltech)’s Palomar Observatory near San Diego, California, and has released its first set of results since it began operations in March 2018. The instrument has observed more than one billion of the stars in the Milky Way and has made a wealth of discoveries, from 50 small near-Earth asteroids to more than 1,100 supernovae.

The ZTF also captured an image of the Andromeda galaxy, the nearest galaxy to our Milky Way at 2.5 million light-years away. Through the combination of three bands of light captured by the ZTF, a composite image was created which shows Andromeda in all is glory:

This new composite image of the Andromeda galaxy was made by combining three bands of visible light captured by the Zwicky Transient Facility (ZTF). The image covers 2.9 square degrees of sky, which is one-sixteenth of ZTF’s full field of view. ZTF/D. Goldstein and R. Hurt/Caltech

The ZFT camera made use of the 48-inch Samuel Oschin Telescope at Palomar to observe the Northern skies in great detail. The camera captures a large amount of the sky in one image — more than 240 times the size of the full moon — so it can pick up rare or brief cosmic events like passing asteroids or exploding supernovae.

This means that scientists can study dramatic events like the destruction of stars: “With the ZTF Northern Sky Survey, we are conducting a systematic study of transients in the nuclei of galaxies, allowing us to catch stars in the act of being ripped apart by supermassive black holes and capture active galactic nuclei ‘turning on’ from a previously quiescent state,” Suvi Gezari, an assistant professor of astronomy at UMD, said in a statement. “We expect to yield enough of these events in the three-year survey to transform our understanding of accretion onto supermassive black holes lurking in the centers of galaxies.”

One of the discoveries made by the ZTF is observing two black holes which are shredding nearby stars. If a star passes too close to a black hole it can experience “tidal disruption” in which the enormous gravity of the black hole stretches the star until it is destroyed.

The team working on tidal disruption have been having some fun with their findings too, by ditching the formal technical names for these black holes: “We decided to nickname them Ned Stark and Jon Snow, after ‘Game of Thrones’ characters,” Matthew Graham, ZTF project scientist at Caltech, said. Let’s hope the black holes survive for longer than their namesake characters.

The findings are published in seven papers in the journal Publications of the Astronomical Society of the Pacific and can also be found online.